gradient color

http://www.cnblogs.com/YouXianMing/p/3793913.html

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layer 不能自动autolay， 只能在viewDidLayout里面设置宽度

- (void) viewDidLayoutSubviews {
  [super viewDidLayoutSubviews]; //if you want superclass's behaviour...
  // resize your layers based on the view's new frame
  self.editViewBorderLayer.frame = self.editView.bounds;
}

　　

gradientLayer = [CAGradientLayer layer];
_gradientLayer.frame = maskedImageView.bounds;
_gradientLayer.colors = colors;

//set locations for the colors
NSArray * startingLocations = @[@0.0, @0.4,@1.0];
NSArray *endinglocations = @[@0.0,@0.8,@1.0];

// Update the model layer to the final point
_gradientLayer.locations = endinglocations;
_gradientLayer.startPoint = CGPointMake(0.0f, 0.3f);
_gradientLayer.endPoint = CGPointMake(1.0f, 0.5f);

//add the text image as a mask on the gradient layer
_gradientLayer.mask = maskedImageView.layer;

//add the gradient layer to the holder view
[_slideImageView.layer addSublayer:_gradientLayer];

　　

location 代表的是分界线， 比如三个的话就为 @[@(0), @(5), @(1)]

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https://github.com/yannickl/DynamicColor

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down vote
accepted
- (UIColor *)lighterColorForColor:(UIColor *)c
{
    CGFloat r, g, b, a;
    if ([c getRed:&r green:&g blue:&b alpha:&a])
        return [UIColor colorWithRed:MIN(r + 0.2, 1.0)
                               green:MIN(g + 0.2, 1.0)
                                blue:MIN(b + 0.2, 1.0)
                               alpha:a];
    return nil;
}

- (UIColor *)darkerColorForColor:(UIColor *)c
{
    CGFloat r, g, b, a;
    if ([c getRed:&r green:&g blue:&b alpha:&a])
        return [UIColor colorWithRed:MAX(r - 0.2, 0.0)
                               green:MAX(g - 0.2, 0.0)
                                blue:MAX(b - 0.2, 0.0)
                               alpha:a];
    return nil;
}

http://stackoverflow.com/questions/11598043/get-slightly-lighter-and-darker-color-from-uicolor

@implementation UIColor (LightAndDark)

- (UIColor *)lighterColor
{
    CGFloat h, s, b, a;
    if ([self getHue:&h saturation:&s brightness:&b alpha:&a])
        return [UIColor colorWithHue:h
                          saturation:s
                          brightness:MIN(b * 1.3, 1.0)
                               alpha:a];
    return nil;
}

- (UIColor *)darkerColor
{
    CGFloat h, s, b, a;
    if ([self getHue:&h saturation:&s brightness:&b alpha:&a])
        return [UIColor colorWithHue:h
                          saturation:s
                          brightness:b * 0.75
                               alpha:a];
    return nil;
}
@end

　　

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CGFloat red, green, blue, alpha;

//Create a sample color

UIColor *redColor = [UIColor redColor];

//Call 

[redColor getRed: &red
  green: &green
  blue: &blue
  alpha: &alpha];
NSLog(@"red = %f. Green = %f. Blue = %f. Alpha = %f",
  red,
  green,
  blue,